Area Vowels (bottom part of page)(页面存档备份,存于互联网档案馆) Sound files at PenelopeEckert's website NPR interview with Professor William Labov about the shift(页面存档备份,存于互联网档案馆)
Cambridge: University of Cambridge Press. 1998. ISBN 978-0-521-59646-6. Eckert, Penelope; Rickford, John R., eds. Style and Sociolinguistic Variation. Cambridge: